#include "sbgCrc.h"

//----------------------------------------------------------------------//
//- Static global CRC tables                                           -//
//----------------------------------------------------------------------//

/*!< CRC table used to compute a 16 bit CRC with the polynom 0x8408. */
static const uint16 crc16LookupTable[256] = {
	0x0000,0x1189,0x2312,0x329B,0x4624,0x57AD,0x6536,0x74BF,0x8C48,0x9DC1,0xAF5A,0xBED3,0xCA6C,0xDBE5,0xE97E,0xF8F7,
	0x1081,0x0108,0x3393,0x221A,0x56A5,0x472C,0x75B7,0x643E,0x9CC9,0x8D40,0xBFDB,0xAE52,0xDAED,0xCB64,0xF9FF,0xE876,
	0x2102,0x308B,0x0210,0x1399,0x6726,0x76AF,0x4434,0x55BD,0xAD4A,0xBCC3,0x8E58,0x9FD1,0xEB6E,0xFAE7,0xC87C,0xD9F5,
	0x3183,0x200A,0x1291,0x0318,0x77A7,0x662E,0x54B5,0x453C,0xBDCB,0xAC42,0x9ED9,0x8F50,0xFBEF,0xEA66,0xD8FD,0xC974,
	0x4204,0x538D,0x6116,0x709F,0x0420,0x15A9,0x2732,0x36BB,0xCE4C,0xDFC5,0xED5E,0xFCD7,0x8868,0x99E1,0xAB7A,0xBAF3,
	0x5285,0x430C,0x7197,0x601E,0x14A1,0x0528,0x37B3,0x263A,0xDECD,0xCF44,0xFDDF,0xEC56,0x98E9,0x8960,0xBBFB,0xAA72,
	0x6306,0x728F,0x4014,0x519D,0x2522,0x34AB,0x0630,0x17B9,0xEF4E,0xFEC7,0xCC5C,0xDDD5,0xA96A,0xB8E3,0x8A78,0x9BF1,
	0x7387,0x620E,0x5095,0x411C,0x35A3,0x242A,0x16B1,0x0738,0xFFCF,0xEE46,0xDCDD,0xCD54,0xB9EB,0xA862,0x9AF9,0x8B70,
	0x8408,0x9581,0xA71A,0xB693,0xC22C,0xD3A5,0xE13E,0xF0B7,0x0840,0x19C9,0x2B52,0x3ADB,0x4E64,0x5FED,0x6D76,0x7CFF,
	0x9489,0x8500,0xB79B,0xA612,0xD2AD,0xC324,0xF1BF,0xE036,0x18C1,0x0948,0x3BD3,0x2A5A,0x5EE5,0x4F6C,0x7DF7,0x6C7E,
	0xA50A,0xB483,0x8618,0x9791,0xE32E,0xF2A7,0xC03C,0xD1B5,0x2942,0x38CB,0x0A50,0x1BD9,0x6F66,0x7EEF,0x4C74,0x5DFD,
	0xB58B,0xA402,0x9699,0x8710,0xF3AF,0xE226,0xD0BD,0xC134,0x39C3,0x284A,0x1AD1,0x0B58,0x7FE7,0x6E6E,0x5CF5,0x4D7C,
	0xC60C,0xD785,0xE51E,0xF497,0x8028,0x91A1,0xA33A,0xB2B3,0x4A44,0x5BCD,0x6956,0x78DF,0x0C60,0x1DE9,0x2F72,0x3EFB,
	0xD68D,0xC704,0xF59F,0xE416,0x90A9,0x8120,0xB3BB,0xA232,0x5AC5,0x4B4C,0x79D7,0x685E,0x1CE1,0x0D68,0x3FF3,0x2E7A,
	0xE70E,0xF687,0xC41C,0xD595,0xA12A,0xB0A3,0x8238,0x93B1,0x6B46,0x7ACF,0x4854,0x59DD,0x2D62,0x3CEB,0x0E70,0x1FF9,
	0xF78F,0xE606,0xD49D,0xC514,0xB1AB,0xA022,0x92B9,0x8330,0x7BC7,0x6A4E,0x58D5,0x495C,0x3DE3,0x2C6A,0x1EF1,0x0F78};

/*!< CRC table used to compute an Ethernet 32 bit CRC using the normal polynom 0x04C11DB7. */
static const uint32 crc32EthernetTable[256] =
{
  0x00000000,
  0x04c11db7, 0x09823b6e, 0x0d4326d9, 0x130476dc, 0x17c56b6b,
  0x1a864db2, 0x1e475005, 0x2608edb8, 0x22c9f00f, 0x2f8ad6d6,
  0x2b4bcb61, 0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd,
  0x4c11db70, 0x48d0c6c7, 0x4593e01e, 0x4152fda9, 0x5f15adac,
  0x5bd4b01b, 0x569796c2, 0x52568b75, 0x6a1936c8, 0x6ed82b7f,
  0x639b0da6, 0x675a1011, 0x791d4014, 0x7ddc5da3, 0x709f7b7a,
  0x745e66cd, 0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039,
  0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5, 0xbe2b5b58,
  0xbaea46ef, 0xb7a96036, 0xb3687d81, 0xad2f2d84, 0xa9ee3033,
  0xa4ad16ea, 0xa06c0b5d, 0xd4326d90, 0xd0f37027, 0xddb056fe,
  0xd9714b49, 0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95,
  0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1, 0xe13ef6f4,
  0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d, 0x34867077, 0x30476dc0,
  0x3d044b19, 0x39c556ae, 0x278206ab, 0x23431b1c, 0x2e003dc5,
  0x2ac12072, 0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16,
  0x018aeb13, 0x054bf6a4, 0x0808d07d, 0x0cc9cdca, 0x7897ab07,
  0x7c56b6b0, 0x71159069, 0x75d48dde, 0x6b93dddb, 0x6f52c06c,
  0x6211e6b5, 0x66d0fb02, 0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1,
  0x53dc6066, 0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
  0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e, 0xbfa1b04b,
  0xbb60adfc, 0xb6238b25, 0xb2e29692, 0x8aad2b2f, 0x8e6c3698,
  0x832f1041, 0x87ee0df6, 0x99a95df3, 0x9d684044, 0x902b669d,
  0x94ea7b2a, 0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e,
  0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2, 0xc6bcf05f,
  0xc27dede8, 0xcf3ecb31, 0xcbffd686, 0xd5b88683, 0xd1799b34,
  0xdc3abded, 0xd8fba05a, 0x690ce0ee, 0x6dcdfd59, 0x608edb80,
  0x644fc637, 0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb,
  0x4f040d56, 0x4bc510e1, 0x46863638, 0x42472b8f, 0x5c007b8a,
  0x58c1663d, 0x558240e4, 0x51435d53, 0x251d3b9e, 0x21dc2629,
  0x2c9f00f0, 0x285e1d47, 0x36194d42, 0x32d850f5, 0x3f9b762c,
  0x3b5a6b9b, 0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff,
  0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623, 0xf12f560e,
  0xf5ee4bb9, 0xf8ad6d60, 0xfc6c70d7, 0xe22b20d2, 0xe6ea3d65,
  0xeba91bbc, 0xef68060b, 0xd727bbb6, 0xd3e6a601, 0xdea580d8,
  0xda649d6f, 0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3,
  0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7, 0xae3afba2,
  0xaafbe615, 0xa7b8c0cc, 0xa379dd7b, 0x9b3660c6, 0x9ff77d71,
  0x92b45ba8, 0x9675461f, 0x8832161a, 0x8cf30bad, 0x81b02d74,
  0x857130c3, 0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640,
  0x4e8ee645, 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c, 0x7b827d21,
  0x7f436096, 0x7200464f, 0x76c15bf8, 0x68860bfd, 0x6c47164a,
  0x61043093, 0x65c52d24, 0x119b4be9, 0x155a565e, 0x18197087,
  0x1cd86d30, 0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
  0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088, 0x2497d08d,
  0x2056cd3a, 0x2d15ebe3, 0x29d4f654, 0xc5a92679, 0xc1683bce,
  0xcc2b1d17, 0xc8ea00a0, 0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb,
  0xdbee767c, 0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18,
  0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4, 0x89b8fd09,
  0x8d79e0be, 0x803ac667, 0x84fbdbd0, 0x9abc8bd5, 0x9e7d9662,
  0x933eb0bb, 0x97ffad0c, 0xafb010b1, 0xab710d06, 0xa6322bdf,
  0xa2f33668, 0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4
};

//----------------------------------------------------------------------//
//- 32 bits Ethernet CRC                                               -//
//----------------------------------------------------------------------//

/*!
 *	Initialize the 32 bit CRC computation system.
 *	\param[in]	pInstance				Pointer on an allocated but non initialized Crc32 object.
 */
void sbgCrc32Initialize(SbgCrc32 *pInstance)
{
	//
	// Test input argument
	//
	SBG_ASSERT(pInstance);

	*pInstance = 0xFFFFFFFF;
}

/*!
 *	Compute a 32 bit CRC using an Ethernet polynome.
 *	Warning: the buffer size should be at least 4 bytes long.
 *	\param[in]	pInstance				Read only pointer on a valid Crc32 object.
 *	\param[in]	pData					Read only pointer on the data buffer to compute CRC on.
 *	\param[in]	dataSize				Data size in bytes of the buffer, has to be greater or equals to 4.
 */
void sbgCrc32Update(SbgCrc32 *pInstance, const void *pData, size_t dataSize)
{
	const uint8		*pBuffer = (const uint8*)pData;
	uint32			 byte;
	size_t			 i;
	size_t			 dataSizeCorrected;
	size_t			 numBytesLeft;

	//
	// Test input arguments
	//
	SBG_ASSERT(pInstance);
	SBG_ASSERT(pData);
	SBG_ASSERT(dataSize >= 4);

	//
	// Compute the data size that corresponds to complete uinht32 and how many bytes remains
	//
	dataSizeCorrected = dataSize & (~0x00000003);
	numBytesLeft = dataSize & 0x03;
	
	// For each byte, update the CRC 
	//
	for (i = 0; i < dataSizeCorrected; i++)
	{
		//
		// Get the current byte value
		//
		byte = pBuffer[i ^ 0x03];

		//
		// Update the CRC value
		//
		*pInstance = (*pInstance << 8) ^ crc32EthernetTable[((*pInstance >> 24) ^ byte) & 0xFF];
	}

	//
	// Test how many bytes remains
	//
	for (i = 0; i < numBytesLeft; i++)
	{
		//
		// Get the current byte value
		//
		byte = pBuffer[dataSizeCorrected + (i ^ (numBytesLeft - 1))];

		//
		// Update the CRC value
		//
		*pInstance = (*pInstance << 8) ^ crc32EthernetTable[((*pInstance >> 24) ^ byte) & 0xFF];
	}
}

/*!
 *	Compute a 32 Bit CRC using an Ethernet polynome.
 *	Warning: the buffer size should be at least 4 bytes long.
 *	\param[in]	pData					Read only pointer on the data buffer to compute CRC on.
 *	\param[in]	dataSize				Data size in bytes of the buffer, has to be greater or equals to 4.
 *	\return								The computed CRC.
 */
uint32 sbgCrc32Compute(const void *pData, size_t dataSize)
{
	SbgCrc32 crcInst;

	//
	// Initialize the CRC system
	//
	sbgCrc32Initialize(&crcInst);

	//
	// Compute the CRC
	//
	sbgCrc32Update(&crcInst, pData, dataSize);

	//
	// Return it
	//
	return sbgCrc32Get(&crcInst);
}

//----------------------------------------------------------------------//
//- CRC-16 operations                                                  -//
//----------------------------------------------------------------------//

/*!
 *	Initialize the 16 bit CRC computation system.
 *	\param[in]	pInstance				Pointer on an allocated but non initialized Crc16 object.
 */
void sbgCrc16Initialize(SbgCrc16 *pInstance)
{
	//
	// Test input argument
	//
	SBG_ASSERT(pInstance);

	*pInstance = 0;
}

/*!
 *	Compute a 16 bit CRC using an the polynome 0x8408.
 *	\param[in]	pInstance				Read only pointer on a valid Crc16 object.
 *	\param[in]	pData					Read only pointer on the data buffer to compute CRC on.
 *	\param[in]	dataSize				Data size in bytes of the buffer.
 */
void sbgCrc16Update(SbgCrc16 *pInstance, const void *pData, size_t dataSize)
{
	const uint8 *pBuffer = (const uint8*)pData;
	uint8 index;
	size_t i;

	//
	// Test input arguments
	//
	SBG_ASSERT(pInstance);
	SBG_ASSERT(pData);

    //
    // For each byte in our buffer
    //
    for (i = 0; i < dataSize; i++)
    {
    	//
    	// Update the current CRC
    	//
        index = (pBuffer[i] ^ *pInstance) & 0xFF;
        *pInstance = crc16LookupTable[index] ^ (*pInstance >> 8);
    }
}

/*!
 *	Compute a 32 Bit CRC using an the polynome 0x8408.
 *	\param[in]	pData					Read only pointer on the data buffer to compute CRC on.
 *	\param[in]	dataSize				Data size in bytes of the buffer.
 *	\return								The computed CRC.
 */
uint16 sbgCrc16Compute(const void *pData, size_t dataSize)
{
	SbgCrc16 crcInst;

	//
	// Initialize the CRC system
	//
	sbgCrc16Initialize(&crcInst);

	//
	// Compute the CRC
	//
	sbgCrc16Update(&crcInst, pData, dataSize);

	//
	// Return it
	//
	return sbgCrc16Get(&crcInst);
}

